This invention relates to an engine control apparatus and a control method useful to drive an engine in the best condition, and particularly to an ignition advance angle control apparatus and control method.
Recently, an engine control apparatus with a microcomputer has been proposed in order to drive the engine in the best condition.
In such an engine control apparatus with a microcomputer, at least two parameters indicative of the operating condition of the engine are each divided into a definite number of values, and the operating condition of the engine is controlled at each combination of these values by an operating condition control means, in which case the basic amount of control that the control means operates from is read from a fixed data memory (generally a read-only memory) in which the basic amounts of control are stored, in accordance with the operating condition of the engine and the operating condition control means is driven on the basis of this basic amount of control.
When the operating condition control means is driven by the basic amount of control stored in such a fixed data memory, an abrupt change of the operating condition of the engine, such as a sudden acceleration or deceleration, will naturally require a change in the combination of parameter values which is applied to the fixed data memory, and during the change, basic amounts of control are read from the fixed memory and used to drive the operating condition control means.
The basic amount of control that the operating condition control means relies upon for controlling the operating condition of the engine is generally a predetermined value for the best control of the operating condition of the engine at that time, but when the operating condition of the engine is suddenly changed by a large amount in a short time, the basic amounts of control read during such abrupt change do not always correspond to the proper operating conditions of the engine at that time.
Therefore, the engine cannot be operated in the best condition by the operating condition control means under such inadequate basic amounts of control.